Antibodies Directed against O-Acetylated Sialoglycoconjugates Accelerate Complement Activation in Leishmania donovani Promastigotes
IR@IICB: CSIR-Indian Institute of Chemical Biology, KolkataView Archive Info
Antibodies Directed against O-Acetylated
Sialoglycoconjugates Accelerate Complement
Activation in Leishmania donovani Promastigotes
Infectious Diseases and Immunology
Background. An enhanced presence of 9-O-acetylated sialoglycoconjugates (9-O-AcSGs) triggers the alternate
pathway (AP) in Indian visceral leishmaniasis (VL). Antibodies directed against these epitopes are present in high
titers. The biological relevance of these antibodies, with regard to activation of the classical pathway (CP), was
Methods. Complement activators were affinity purified, complement activation via the CP, AP, and lectinmediated
complement pathway was measured by use of an anti-C3 radio-binding assay, and the number of C3
molecules was quantitated by Scatchard analysis. Cell death induced via the complement pathways was measured
by use of MTT (tetrazolium salt 3- [4, 5-dimethylthiazol-2-yl] -2, 5-diphenyltetrazolium bromide) assay, and
uptake of propidium iodide (PI) was measured by flow cytometry.
Results. Anti–O-AcSGs from both healthy donors and patients with VL elicited C3 deposition as early as 3
min, which triggered parasite lysis, as demonstrated by use of MTT assay and corroborated by the high rate of
uptake of PI. Analysis of complement activation by mannan-binding lectin and C-reactive protein demonstrated
their negligible contribution during the 3-min time frame.
Conclusions. Anti–O-AcSGs were identified as an important source of CP activation under normal physiological
conditions, suggesting that they play a role in conferring host protection against parasite infection.
Bandyopadhyay, Sumi and Chatterjee, Mitali and Das, Tanusree and Bandyopadhyay, Suman and Sundar, Shyam and Mandal, Chitra (2004) Antibodies Directed against O-Acetylated Sialoglycoconjugates Accelerate Complement Activation in Leishmania donovani Promastigotes. The Journal of Infectious Diseases , 190 (11). pp. 2010-2019.